Tribulus produces small yellow flowers and fruit that are covered with spines. In some countries it is commonly known as the ‘puncture vine’ because the sharp spines can flatten bicycle tyres.
The ancient Greeks used tribulus as a diuretic and mood-enhancer, and it has been used as a traditional medicine in India and China for centuries. Today it is primarily taken to improve athletic performance, sexual function in men, and to lower blood sugar levels.
Tribulus contains many nutrients, including alkaloids and amino acids, however the most bioactive compound in tribulus is the steroidal saponins, in particular protodioscin. This phytochemical can raise the production of nitric oxide in the body, a molecule which is crucial to blood vessel health.
Nitric oxide is a vasodilator—it relaxes the inner muscles of the blood vessels, causing them to widen. This can enhance the distribution of nutrients and oxygen to muscles during exercise and boost performance as a result.
Nitric oxide is also an important part of men’s sexual health as it enables the muscles in the penis to relax, allowing uninterrupted blood to flow to this area. A study published in 2017 reported that men with mild or moderate erectile dysfunction experienced a substantial improvement in sexual function after taking tribulus for 12 weeks.
Tribulus also has the potential to lower blood glucose levels. For this study, 98 women with type 2 diabetes were given either a tribulus extract or a placebo, for 3 months. At the end of the trial, researchers found that the women who took the tribulus extract had lower blood sugar and cholesterol levels.